Dog trainers and behaviourists say that all that socialisation is necessary. Dogs should go to as many different places as possible and meet lots of people and other dogs. I agree that at first puppies will not be going out so much because of their innoculations but if someone got a puppy at the beginning of first lockdown that puppy will now be a year old. Of course not all dogs will have problems but it is very likely that a lot will. Lots of my friends and neighbours have dogs and you can tell the difference in the ones that were socialised well and the ones that weren't
You can socialise a dog without having it all out everywhere all the time. And no one has been in complete lockdown for a year where they can't be out and about at all.
Most dogs, who turn out perfectly fine, spend time at home, maybe in some parks, to the vets, around their neighbourhood on a lead, and maybe to friend's places occasionally. They may or may not go into urban settings depending on where they live.
All of that has been perfectly possible for the vast majority of the past year.
It's better if they can meet other dogs, but if you want them to get on with other dogs, but again - that has been possible in the past year, too.
Any trainer that tells you you need to be in classes, doggy daycare, going off to all kinds of shops and festivals or whatever, to have a balanced dog, is trying to sell you something.